Finished lubricants used for automobiles, diesel engines, axles, transmissions, and industrial applications consist of two general components, a lubricant base oil and additives. Lubricant base oil is the major constituent in these finished lubricants and contributes significantly to the properties of the finished lubricant. In general, a few lubricant base oils are used to manufacture a wide variety of finished lubricants by varying the mixtures of individual lubricant base oils and individual additives.
Numerous governing organizations, including Original Equipment Manufacturers (OEMs), the American Petroleum Institute (API), Association des Consructeurs d' Automobiles (ACEA), the American Society of Testing and Materials (ASTM), and the Society of Automotive Engineers (SAE), among others, define the specifications for lubricant base oils and finished lubricants. Increasingly, the specifications for finished lubricants are calling for products with excellent low temperature properties, high oxidation stability, and low volatility. Currently, only a small fraction of the lubricant base oils manufactured today are able to meet these demanding specifications.
Lubricant base oils are lubricant base oils having a viscosity of about 3 cSt or greater at 100° C., for example, about 4 cSt or greater at 100° C.; a pour point of about 9° C. or less, for example, about −15° C. or less; and a viscosity index (VI) that is usually about 90 or greater, for example, about 100 or greater. In general, lubricant base oils should have a Noack volatility no greater than current conventional Group I or Group II light neutral oils. Group II lubricant base oils are defined as having a sulfur content of equal to or less than 300 ppm, saturates equal to 90% or greater, and a VI between 80 and 120. Group III lubricant base oils are defined as having a sulfur content of equal to or less than 300 ppm, saturates equal to 90% or greater, and a VI of greater than 120.
Lubricant base oils refer to a hydrocarbon product having the above properties prior to the addition of additives. One class of additives are pour point depressants. Pour point is the lowest temperature at which movement of the lubricant base oil is observed. In order to meet the relevant pour point specification for a finished lubricant, it is often necessary to lower the pour point of the lubricant base oil by the addition of a pour point depressant. Pour point depressants are typically polymers with pendant hydrocarbon chains that interact with the paraffins in the lubricant base oil by inhibiting the formation of large wax crystal lattices. They generally have a wax-like paraffinic part, which co-crystallizes with the wax-forming components in the oil, and a polar part which hinders crystal growth. Examples of pour point depressants known in the art are ethylene-vinyl-acetate copolymers, vinyl-acetate olefin copolymers, alkyl-esters of styrene-maleic-anhydride copolymers, alkyl-esters of unsaturated-carboxylic acids, polyalkylacrylates, polyalklymethacrylates, alkyl phenols, and alpha-olefin copolymers. Many pour point depressants are solid at ambient temperature and must be diluted with solvent prior to use. Conventional pour point depressants are expensive adding significantly to the cost of preparing the finished lubricant.
Thus, there is a need for a less costly process for preparing a pour point depressant.
Additionally, there is a need for a process for preparing a pour point depressant that uses an inexpensive and readily available feedstock. There is also a need for a process for preparing a pour point depressant that provides a significant yield of the pour point depressant